The use of such biomaterial articles as substitute blood vessels, synthetic and intraocular lenses, electrodes, catheters, orthopedic implants and the like in and onto the body is a rapidly developing area of medicine. A primary impediment to the use of such biomaterial devices has been the lack of satisfactory biocompatibility of the device surfaces. The uncoated surfaces of catheters made from plastics, for example, often stimulate rapid thrombogenic action. Various plasma proteins play a role in initiating platelet and fibrin deposition on plastic surfaces and these actions, and the inflammatory reaction that follows, can lead to the loss of function of the device. A “medical device” may be defined as a material that is substantially insoluble in body fluids and that is designed and constructed to be placed in or onto the body or to contact fluid of the body. Catheters, grafts, stents, implants, wound dressings, cardiac valves and intravenous tubing are examples of medical devices.
A medical device surface can desirably have the following characteristics: The device surface will not generally induce undesirable reactions in the body such as blood clotting, tissue death, tumor formation, allergic reaction, foreign body reaction (rejection) or inflammatory reaction. The device surface can be fabricated and sterilized easily such as by autoclave heat sterilization. The device surface does not substantially alter the function of the underlying device during the time that it remains implanted in or in contact with the body, whether it be an hour or a lifetime. The surface or surface coating is nontoxic to the tissues it is in contact with. In the case of a device with an optical function, the surface will be optically clear to allow proper function.
As used herein, the solid surface of a biomaterial is characterized as “biocompatible” if it is capable of functioning or existing in contact with biological fluid and/or tissue of a living organism with a net beneficial effect on the living organism. Long-term biocompatibility is desired for the purpose of reducing disturbance of the host organism.
A number of approaches have been suggested to improve the biocompatibility of implantable items. One approach has been to modify the surface of a biomaterial to prevent undesirable protein adhesion by providing the biomaterial with a protein resistant surface. For example, a contact lens may bind proteins on the lens to create protein deposits in the eye area. Additionally, the lens can cause structural changes including protein denaturation that can elicit an immune response such as tearing, reddening, or swelling in the ocular region. Accordingly, contemplated embodiments provide for medical devices and methods of making devices with improved resistance to undesirable protein interactions and other interactions at the surface.